EP0217509B1 - Self-zeroing transducer assemblies - Google Patents

Self-zeroing transducer assemblies Download PDF

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Publication number
EP0217509B1
EP0217509B1 EP86305962A EP86305962A EP0217509B1 EP 0217509 B1 EP0217509 B1 EP 0217509B1 EP 86305962 A EP86305962 A EP 86305962A EP 86305962 A EP86305962 A EP 86305962A EP 0217509 B1 EP0217509 B1 EP 0217509B1
Authority
EP
European Patent Office
Prior art keywords
pressure
lines
pressure transducer
zeroing
transducer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP86305962A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0217509A2 (en
EP0217509A3 (en
Inventor
Edward Bastijanic
Edward Lee Sterling, Jr.
John Walter Robertson, Jr.
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
INTERNATIONAL CONTROL AUTOMATION FINANCE SA
Original Assignee
International Control Automation Finance SA Luxembourg
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by International Control Automation Finance SA Luxembourg filed Critical International Control Automation Finance SA Luxembourg
Publication of EP0217509A2 publication Critical patent/EP0217509A2/en
Publication of EP0217509A3 publication Critical patent/EP0217509A3/en
Application granted granted Critical
Publication of EP0217509B1 publication Critical patent/EP0217509B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q1/00—Details of selecting apparatus or arrangements
    • H04Q1/18—Electrical details
    • H04Q1/28—Current-supply circuits or arrangements for selection equipment at exchanges
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L27/00—Testing or calibrating of apparatus for measuring fluid pressure
    • G01L27/002—Calibrating, i.e. establishing true relation between transducer output value and value to be measured, zeroing, linearising or span error determination
    • G01L27/005—Apparatus for calibrating pressure sensors

Definitions

  • This invention relates to self-zeroing pressure transducer assemblies or transmitters.
  • Two-wire analog transmission systems are known. Such systems include a transmitter which is connected to a power supply by two wires which form a current loop.
  • the transmitter includes, as at least one of its features, a transducer which senses a condition such as pressure or temperature. This condition is known as a process variable (PV).
  • PV process variable
  • a power supply is connected to the two wires to close the current loop. It is also known to provide a resistor in the current loop.
  • the transmitter amplifies the signal from its transducer and this amplified signal is used to draw a certain current from the power supply which is proportional or otherwise related to the process variable. It is known to draw from a minimum of 4 mA to a maximum of 20 mA.
  • the current between 4 and 20 mA passes through the resistor to produce a voltage drop across the resistor. This voltage drop can be measured to give a value for the process variable.
  • the 4 mA minimum current is required to energise the circuitry of the transmitter. Any excess current above this 4 mA level is taken as a value which can be used to determine the process variable.
  • the transmitters in such circuits are generally limited in accuracy to about 0.1% and their functionality is limited to only continuous reading and sensing of the process variable.
  • US Patent No US-A-3 509 767 discloses a self-zeroing pressure transducer assembly comprising: a pressure transducer having two inputs; a first pressure line connected to a first of the two inputs; a second pressure line connected to the second of the two inputs; a first valve in the first pressure line; a second valve in the second pressure line; a pressure equalising connecting line connected between the first and second pressure lines at a point on the first and second pressure lines between the first and second valves and the transducer; a pressure equalising valve in the connecting line; a switch means connected to the first valve and the pressure equalising valve and functioning, upon receiving one control signal, to open the first valve while maintaining the pressure equalising valve closed whereby the two inputs of the pressure transducer are exposed to separate pressures on the first and second pressure lines, and, upon receiving another control signal, to close the first valve while opening the pressure equalising valve so as to equalise the pressure between the first and second pressure lines and thus equalise the pressure at the two inputs of the transduc
  • a self-zeroing pressure transducer assembly characterised in that said control means is operable to generate said other control signal after a preselected time interval or when desired by a user and the control means comprises a microprocessor which is responsive to the value of the pressure signal produced by the pressure transducer when the switch means receives said other control signal to provide self-zeroing of the pressure transducer assembly by recalibrating the pressure transducer assembly such that, when said one control signal is thereafter generated, said value of the pressure signal is treated as a zero indication for the pressure transducer until said other signal is again generated, wherein the microprocessor is operative to generate said other control signal, in place of said one control signal, each time that a preselected maintenance time interval, in accordance with suspected drift of the pressure transducer from its zero position, has elapsed.
  • US-A-3 509 767 also discloses a method of operating a pressure transducer assembly having a transducer with two inputs for receiving two separate pressures on two separate pressure lines, the method comprising: establishing communication between the two separate pressure lines while closing off communication between external separate pressures connected to the pressure lines and the pressure transducer for equalising a pressure between the first and second pressure lines; measuring an output signal from the transducer with the communication established between the first and second pressure lines; and utilising the measured output signal from the transducer assembly to effect self-zeroing of the pressure transducer assembly.
  • a method as just described characterised in that communication between the two separate pressure lines is established after a preselected time interval or when desired by a user and said utilisation step comprises supplying the measured output signal to a microprocessor which is responsive to the value of the measured output signal to provide self-zeroing of the pressure transducer assembly by recalibrating the pressure transducer assembly such that, when said communication between the two separate pressure lines is thereafter disestablished, said value of the measured output signal is treated as a zero indication for the pressure transducer until said communication between the two separate pressure lines is again established, and in that the microprocessor is operative to cause said disestablishment of the communication between the two separate pressure lines after recalibration, wherein the microprocessor establishes said communication between the two separate pressure lines each time that a preselected maintenance time interval, in accordance with suspected drift of the pressure transducer from its zero position, has elapsed.
  • the sole figure of the drawing shows a pressure transducer arrangement which includes a so-called smart transmitter 10 that incorporates a differential pressure transducer or pressure sensor 12 having two inputs 14 and 16 for receiving two separate pressures P1 and P2, respectively, and for generating a signal on a line 18 which corresponds to or is proportional to the difference between the pressures P1 and P2.
  • a so-called smart transmitter 10 that incorporates a differential pressure transducer or pressure sensor 12 having two inputs 14 and 16 for receiving two separate pressures P1 and P2, respectively, and for generating a signal on a line 18 which corresponds to or is proportional to the difference between the pressures P1 and P2.
  • the smart transmitter 10 includes a control circuit 20, which is a microprocessor, such as a Motorola 6800 based processor or an Intel 80C51, and which receives the signal on the line 18 and outputs a signal on a line 22 which can for example be utilised on a two-wire current loop.
  • a control circuit 20 which is a microprocessor, such as a Motorola 6800 based processor or an Intel 80C51, and which receives the signal on the line 18 and outputs a signal on a line 22 which can for example be utilised on a two-wire current loop.
  • the microprocessor 20 is connected by a line 24 to a switch means 26.
  • the switch means 26 is incorporated in a pressure manifold 30, such as Anderson Greenwood's remote actuating manifold.
  • a first pressure line 32 conveys the pressure P1 to the input 14 of the sensor 12.
  • a second pressure line 34 conveys the pressure P2 to the other input 16 of the sensor 12.
  • the first and second pressure lines 32,34 pass through the manifold 30.
  • a first valve 36 is in the first pressure line 32 and a second valve 38 is in the second pressure line 34.
  • a connecting line 40 interconnects the first and second pressure lines 32,34 at a point between the inputs 14,16 of the sensor 12 and the valves 36,38.
  • the connecting line 40 is provided with an equalising valve 28.
  • the switching means 26 Upon receipt of signals from the microprocessor 20 on the line 24, the switching means 26 operates to open the valves 36 and 38 while maintaining the valve 28 closed. This exposes the inputs 14 and 16 of the sensor 12 to the pressures P1 and P2 so that the sensor 12 can generate its signal on the line 18.
  • a signal is provided on the line 24 from the microprocessor 20 to the switching means 26 to close the valve 36 while opening the valve 28. This blocks the lower pressure P1 while establishing a communication over the line 40 between the first and second pressure lines 32,34. This automatically equalises the pressures in the lines 32 and 34 where they communicate with the pressure transducer 12.
  • the signal on the line 18 is treated, by the microprocessor 20, to be a zero indication for the transducer 12. This effects a recalibration of the smart transmitter 10.
  • a control signal is provided on the line 24 to the switch means 26 to open the valves 36,38 and simultaneously to close the valve 28. Once exposed to the pressures P1 and P2, any changes in the signal from the sensor 12 on the line 18 are interpreted and correspond to pressure differences between P1 and P2.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Measuring Fluid Pressure (AREA)
  • Control Of Fluid Pressure (AREA)
  • Arrangements For Transmission Of Measured Signals (AREA)
EP86305962A 1985-08-12 1986-08-01 Self-zeroing transducer assemblies Expired - Lifetime EP0217509B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US06/764,916 US4655074A (en) 1985-08-12 1985-08-12 Self-zeroing pressure transmitter with automatic pressure manifold
US764916 1985-08-12

Publications (3)

Publication Number Publication Date
EP0217509A2 EP0217509A2 (en) 1987-04-08
EP0217509A3 EP0217509A3 (en) 1988-04-27
EP0217509B1 true EP0217509B1 (en) 1994-10-05

Family

ID=25072158

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86305962A Expired - Lifetime EP0217509B1 (en) 1985-08-12 1986-08-01 Self-zeroing transducer assemblies

Country Status (10)

Country Link
US (1) US4655074A (enrdf_load_stackoverflow)
EP (1) EP0217509B1 (enrdf_load_stackoverflow)
JP (1) JPS6238336A (enrdf_load_stackoverflow)
KR (1) KR940010207B1 (enrdf_load_stackoverflow)
AU (2) AU585363B2 (enrdf_load_stackoverflow)
BR (1) BR8603174A (enrdf_load_stackoverflow)
CA (1) CA1274102A (enrdf_load_stackoverflow)
DE (1) DE3650086T2 (enrdf_load_stackoverflow)
IN (1) IN163066B (enrdf_load_stackoverflow)
MX (1) MX167954B (enrdf_load_stackoverflow)

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4604566A (en) * 1985-08-07 1986-08-05 The Babcock & Wilcox Company Voltage pulse to current regulating convertor
US4817022A (en) * 1986-07-30 1989-03-28 Barber-Colman Company Method and apparatus for automatic offset compensation in parameter-sensing transducer systems
FR2651318B2 (fr) * 1988-06-03 1994-11-18 Karlsruhe Augsburg Iweka Ensemble perfectionne de detection et de mesure de la pression et de la temperature dans un fluide sous pression.
US6069594A (en) * 1991-07-29 2000-05-30 Logitech, Inc. Computer input device with multiple switches using single line
JP2615532B2 (ja) * 1991-09-04 1997-05-28 動力炉・核燃料開発事業団 高精度差圧測定装置における零点補正方法
US5596147A (en) * 1995-11-17 1997-01-21 Wilda; Douglas W. Coplanar pressure sensor mounting for remote sensor
US5668322A (en) * 1996-06-13 1997-09-16 Rosemount Inc. Apparatus for coupling a transmitter to process fluid having a sensor extension selectively positionable at a plurality of angles
US6672130B2 (en) * 2001-09-08 2004-01-06 Dresser, Inc. Pressure generator for portable instrument
US20040206154A1 (en) * 2002-05-16 2004-10-21 Kosh William Stephen Portable differential pressure generator
US7111491B2 (en) * 2001-09-08 2006-09-26 Ashcroft Inc. Portable differential pressure generator
JP2005273389A (ja) * 2004-03-26 2005-10-06 Toli Corp 壁面施工用部材及び壁面の施工方法
WO2007056457A2 (en) 2005-11-09 2007-05-18 Combinatorx, Incorporated Methods, compositions, and kits for the treatment of medical conditions
DE102012112425A1 (de) * 2012-12-17 2014-07-03 Endress + Hauser Gmbh + Co. Kg Verfahren zur Erfassung und Korrektur einer Nullpunktverschiebung eines Druckmessgerätes
DE102013114495A1 (de) * 2013-12-19 2015-06-25 S.K.I. GmbH Verfahren sowie Messanordnung nach dem Differenzdruckprinzip mit Nullpunktabgleich
CN112045548B (zh) * 2020-08-24 2022-09-06 华海清科股份有限公司 用于化学机械抛光的晶圆承载装置和化学机械抛光设备

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1182137A (en) * 1967-07-04 1970-02-25 Mercury Electronics Scotland L Improvements in Manometers or Pressure Transducers
US4466290A (en) * 1981-11-27 1984-08-21 Rosemount Inc. Apparatus for conveying fluid pressures to a differential pressure transducer
US4476707A (en) * 1982-04-08 1984-10-16 Bear Medical Systems, Inc. Gas flow measurement with detented chopper valve
US4494183A (en) * 1982-06-17 1985-01-15 Honeywell Inc. Process variable transmitter having a non-interacting operating range adjustment
EP0101528B1 (en) * 1982-08-19 1989-11-08 Honeywell Inc. Improvements in 2-wire analog communication systems
FR2544071B1 (fr) * 1983-04-05 1985-06-14 Desbordes A Ets Appareil de mesure de pression differentielle
US4576035A (en) * 1984-01-05 1986-03-18 Cordis Corporation Self-calibrating differential condition sensor
US4607247A (en) * 1985-08-12 1986-08-19 The Babcock & Wilcox Company On-line serial communication interface from a transmitter to a current loop
US4729125A (en) * 1985-08-12 1988-03-01 The Babcock & Wilcox Company On-line serial communication interface to a transmitter from a current loop

Also Published As

Publication number Publication date
DE3650086T2 (de) 1995-04-06
AU581325B2 (en) 1989-02-16
US4655074A (en) 1987-04-07
KR940010207B1 (ko) 1994-10-22
JPS6238336A (ja) 1987-02-19
MX167954B (es) 1993-04-26
EP0217509A2 (en) 1987-04-08
IN163066B (enrdf_load_stackoverflow) 1988-08-06
DE3650086D1 (de) 1994-11-10
JPH0580974B2 (enrdf_load_stackoverflow) 1993-11-11
EP0217509A3 (en) 1988-04-27
BR8603174A (pt) 1987-03-17
KR870002734A (ko) 1987-04-06
AU585363B2 (en) 1989-06-15
AU5942286A (en) 1987-02-19
AU5942086A (en) 1987-02-19
CA1274102A (en) 1990-09-18

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